AD7873ACP:  触摸屏数字转换器

The is a 12-bit successive approximation ADC with a synchronous serial interface and low on resistance switches for driving touch screens. The AD7873 operates from a single 2.2 V to 5.25 V power supply and features throughput rates greater than 125 kSPS.

The AD7873 features direct battery measurement, temperature measurement, and touch pressure measurement. The AD7873 also has an on-board reference of 2.5 V that can be used for the auxiliary input, battery monitor, and temperature measurement modes. When not in use, the internal reference can be shut down to conserve power. An external reference can also be applied and can be varied from 1 V to VCC and the analog input range is from 0 V to VREF. The device includes a shutdown mode that reduces the current consumption to less than 1 µA.

The AD7873 features on-board switches. This, coupled with low power and high speed operation, makes the device ideal for battery-powered systems such as personal digital assistants with resistive touch screens and other portable equipment. The part is available in a 16-lead, 0.15" quarter size outline package (QSOP), a 16-lead, thin shrink small outline package (TSSOP), and a 16-lead, lead frame chip scale package (LFCSP).

AD7877是一款12位逐次逼近型ADC,具有同步串行接口以及用于驱动触摸屏的低导通电阻开关,采用2.7 V至5.25 V单电源供电（2.2 V也可正常运转）,吞吐量为125 kSPS。AD7877可用于两个输入上的电池测量、温度测量和触摸压力测量。

AD7877还具有一个2.5 V片上基准电压源。不使用时,可关断基准电压源以降低功耗。也可以使用外部基准电压,并可在1 V至+VCC范围内变化,模拟输入范围为0 V至VREF。这款器件具有关断模式,此模式下功耗不足1 µ*。

*上ADC的相位采集通过STOPACQ引脚来控制,这样可以降低来自LCD的噪声影响。用户可编程转换控制包括可变采集时间及{dy}转换延迟。每次转换可利用多达16个均值。该器件还有一个片上DAC,用来控制LCD背光或对比度。AD7877采用转换序列器与定时器,可在从模式或主模式下工作,非常适用于电池供电系统,如带电阻触摸屏的个人数字助理及其它便携式设备。

该器件提供两种封装：32引脚架构芯片级封装（LFCSP）和25引脚晶圆级芯片规模封装（WLCSP）。

1. Ratiometric conversion mode available, eliminating errors due to on-board switch resistances.
2. On-board temperature sensor: −40°C to +85°C.
3. Battery monitor input.
4. Touch pressure measurement capability.
5. Low power consumption of 1.37 mW maximum with the reference off, or 2.41 mW typical with the reference on, at 125 kSPS and VCC at 3.6 V.
6. Package options include 4 mm × 4 mm LFCSP.
7. Analog input range from 0 V to VREF.
8. Versatile serial I/O ports.
9. 个人数字助理
10. 智能手持式设备
11. 触摸屏监控器
12. POS终端机 、
13. 医疗设备
14. 蜂窝电话
15. 寻呼机

AD7873ACP 特性

• 4线触摸屏接口
• LCD降噪特性（STOPACQ引脚）
• 自动转换序列器与定时器
• 用户可编程的转换参数
• 片内温度传感器：-40°C至+85°C
• 2.5 V片内基准电压源
• 片内8位DAC
• 3个辅助模拟输入
• 1个专用GPIO和3个可选GPIO
• 2个电池测量通道（0.5 V至5 V）
• 3个中断输出
• 触摸压力测量

AD7873 芯片订购指南

• 民用温度范围：0 ºC～＋70 ºC
• xx温度范围：－55ºC ～＋125ºC
• 工业用温度范围：不同型号的产品的温度范围可能不同。
• 汽车工作温度范围：-40 ℃～ +125 ℃

AD7873ACP 应用技术支持与电子电路设计开发资源下载

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